Hydrolysis-Induced Aqueous Gelcasting of Magnesium Aluminate Spinel

This paper reports on the synthesis of magnesium aluminate spinel (MAS) powders and consolidation of MAS ceramics by hydrolysis-induced aqueous gelcasting (GCHAS). The MAS powders surface passivated against hydrolysis were dispersed in an aqueous-organic premix solution using suitable dispersants. The consolidation of green bodies occurred under ambient conditions by adding a polymerization initiator, a catalyst, and AlN (0-4.06 wt%) as a cosetting agent. Green samples with exceptionally high green strength (similar to 21 MPa) were obtained in the presence of 4.06 wt% AlN. Sintered (1650 degrees C, 1 h) MAS ceramics consolidated by GCHAS exhibited mechanical properties that are comparable to those consolidated by dry pressing.